Open Access Available online http://ccforum.com/content/13/6/R204 Page 1 of 14 (page number not for citation purposes) Vol 13 No 6 Research The incidence of sub-optimal sedation in the ICU: a systematic review Daniel L Jackson 1 , ClareWProudfoot 2 , Kimberley F Cann 2 and Tim S Walsh 3 1 GE Healthcare, Pollards Wood, Nightingales Lane, Chalfont St. Giles, Bucks, HP8 4SP, UK 2 Heron Evidence Development Ltd, Building 210A, Butterfield Technology and Business Park, Luton, LU2 8DL, UK 3 Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 2SA, UK Corresponding author: Daniel L Jackson, Daniel.Jackson@ge.com Received: 20 Jul 2009 Revisions requested: 29 Sep 2009 Revisions received: 12 Oct 2009 Accepted: 16 Dec 2009 Published: 16 Dec 2009 Critical Care 2009, 13:R204 (doi:10.1186/cc8212) This article is online at: http://ccforum.com/content/13/6/R204 © 2009 Jackson et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0 ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Introduction Patients in intensive care units (ICUs) are generally sedated for prolonged periods. Over-sedation and under- sedation both have negative effects on patient safety and resource use. We conducted a systematic review of the literature in order to establish the incidence of sub-optimal sedation (both over- and under-sedation) in ICUs. Methods We searched Medline, Embase and CINAHL (Cumulative Index to Nursing and Allied Health Literature) online literature databases from 1988 to 15 May 2008 and hand- searched conferences. English-language studies set in the ICU, in sedated adult humans on mechanical ventilation, which reported the incidence of sub-optimal sedation, were included. All abstracts were reviewed twice by two independent reviewers, with all conflicts resolved by a third reviewer, to check that they met the review inclusion criteria. Full papers of all included studies were retrieved and were again reviewed twice against inclusion criteria. Data were doubly extracted. Study aims, design, population, comparisons made, and data on the incidence of sub-optimal, optimal, over-sedation or under- sedation were extracted. Results There was considerable variation between included studies in the definition of optimal sedation and in the scale or method used to assess sedation. Across all included studies, a substantial incidence of sub-optimal sedation was reported, with a greater tendency toward over-sedation. Conclusions Our review suggests that improvements in the consistent definition and measurement of sedation may improve the quality of care of patients within the ICU. Introduction The majority of mechanically ventilated patients within the intensive care unit (ICU) receive sedative drugs. Sedation is administered to ensure patient comfort, reduce anxiety, and facilitate treatments. Optimising sedation management is rec- ognised as important in improving patient outcomes [1]. Under-sedated patients may become agitated and distressed and are at risk of adverse events such as extubation [2-4], whereas over-sedation can prolong time to recovery [1,5]. Assessment of sedation level is carried out mainly by nurses or critical care physicians by assessing patient responses to sim- ple stimuli. Sedation scales such as the Ramsay scale or the Richmond Agitation-Sedation Scale (RASS) are widely used [6-8]. However, there is no universally accepted standard, and this can make comparison between different studies or ICUs difficult [2]. Furthermore, some of these scales have not been fully validated in ICU patients [4]. Recently, devices such as the bispectral index monitor (BIS), which aim to assess seda- tion levels more objectively, have been introduced. However, most studies of BIS have been performed in surgical settings, and to date its effectiveness is not fully proven [8-10]. Available guidelines on sedation typically provide limited guid- ance on optimal sedation monitoring and levels. This is at least partly because optimal sedation levels differ between patients according to their clinical circumstances, and therefore seda- tion practice is ideally individually tailored to each patient, as recommended by several guidelines [2,11,12]. However, among guidelines that do recommend an optimal level of BIS: bispectral index monitor; ICU: intensive care unit; RASS: Richmond Agitation-Sedation Scale; RCT: randomised controlled trial. Critical Care Vol 13 No 6 Jackson et al. Page 2 of 14 (page number not for citation purposes) sedation, there are discrepancies, indicating a lack of consen- sus on this issue. For example, of a survey of available guide- lines, one [13] recommended a sedation level of 2 or 3 on the Ramsay scale, whereas one recommended a goal of RASS -3 for an intubated patient [14] and a second recommended a goal of RASS 0 to -2 [15]. A number of guidelines stress the importance of establishing a set protocol for the sedation of ICU patients [16,17] but do not set out such a protocol in detail, leaving it to individual institutions, and more recent guidelines recognise the benefit of regular (daily) interruption of sedation for eligible patients [11,14,18,19] within sedation protocols. It is recognised that optimising sedation practice is a recog- nised quality marker for intensive care treatment, and proce- dures designed to optimise patient sedation state, such as daily sedation breaks and more frequent monitoring, are key elements of recent quality improvement initiatives. However, despite these recent efforts to improve the quality of sedation practice in the ICU, the epidemiology of sedation, and specif- ically the prevalence of over- or under-sedation, is unclear. To investigate this further, we carried out a systematic review of the publicly available literature to identify the reported inci- dence of sub-optimal sedation. Materials and methods Searching Medline, Embase and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases were searched from 1988 to 15 May 2008 using terms for sedation, ICU, sedation quality management, and sub-optimal sedation. The standard Scottish Intercollegiate Guidance Network (SIGN) filters for randomised controlled trials (RCTs), economic stud- ies and observational studies [20] were combined to capture all study designs relevant to the study question. Full details of the search strategy used are available from the authors on request. Conference proceedings from 2005 through 2008 were hand-searched for relevant studies. All results were uploaded into a bespoke internet SQL (structured query lan- guage)-based database. Selection criteria Inclusion of studies was according to a predetermined set of criteria. To be included, studies had to be in adult humans who were sedated and undergoing mechanical ventilation within the ICU and furthermore had to report the incidence of sub- optimal sedation, over- or under-sedation, or of optimal seda- tion, as defined by the study. Studies that reported the impact of sedation practice on outcomes were also included; these data are reported separately. In addition, short-term studies (including only patients sedated less than 24 hours) were excluded. Only English-language studies were included. To check that they met the review inclusion criteria, all abstracts were reviewed twice by two independent reviewers, with all conflicts resolved by a third reviewer. Full papers of all included studies were retrieved and were again reviewed twice to ensure that they met inclusion criteria. Studies included at this stage were classified as to which aspect of the review question they met, and appropriate data were extracted, summarised and analysed. Data extraction Data were extracted by two reviewers and checked by a third reviewer against the original studies. For all studies, the follow- ing data were extracted: country, sponsor, study design, patient population, objective, number of patients in the study, details of comparisons made (such as between different treat- ment arms or between different sedation monitoring systems), and the proportion of measurements, patients, or time in which patients were judged to be optimally sedated, sub-optimally sedated, over-sedated, or under-sedated. Quantitative data synthesis Due to the wide range of included study types, no studies were suitable for quantitative data synthesis. Results Systematic review study flow The flow of studies through the systematic review is docu- mented in the QUOROM (Quality of Reporting of Meta-Analy- ses) diagram in Figure 1. Seventy-five primary and seven secondary studies met the inclusion criteria. Of these, 18 did not provide any data; either they did not contain data on the outcomes extracted in this review or they did not provide these data in quantitative form. Thirty-six studies reported data on the incidence of sub-optimal sedation. The remainder reported the impact of sedation practice on outcomes; these data are reported separately. Of the included studies, three were Figure 1 The QUOROM (Quality of Reporting of Meta-Analyses) diagram illus-trates the flow of studies through the systematic reviewThe QUOROM (Quality of Reporting of Meta-Analyses) diagram illus- trates the flow of studies through the systematic review. 2967 ci t at i o ns from literature databases 1964 citations excluded at 1 st pass 10 citations from conferences 88 citations excluded at 2 nd pass 2124 ci t at i o ns after eliminating dupli cates 160 citations ordered for full- text review 82 citations included (75 primary studi es) 36 studies reported incidence of inappropriate sedat i on; 3 seco ndary publications 18 st udi es report ed i mpact of sedation practice on outcomes only; 4 secondary publicati ons 21 studies di d not report any outcomes of interest  Available online http://ccforum.com/content/13/6/R204 Page 3 of 14 (page number not for citation purposes) cohort studies that specifically investigated the epidemiology of sedation, 23 were studies investigating anaesthetic drugs (of which 19 were RCTs and four were observational studies), six studies compared sedation monitoring devices or scales (of which one was an RCT and the remainder were observa- tional studies), three studies investigated the introduction of sedation guidelines, and one did not fit any of these catego- ries. The majority of studies (20) were published after 2002, indicating the increasing interest in the practice of sedation quality in recent years, in particular following the publication of updated sedation guidelines from the American College of Critical Care Medicine [2,6]. Definitions of adequate sedation To assess the incidence of sub-optimal sedation, it is neces- sary to consider the definition of what constitutes optimal sedation. We used the definition of optimal sedation (and con- sequently of what constituted sub-optimal sedation) provided by individual studies due to the fact that optimal sedation lev- els will vary according to study setting (for example, between neurological ICU and medical ICU). Across all of the studies, 13 different sedation scales were used to assess sedation quality; additionally, nurse assess- ment of sedation quality simply as over-sedated, under- sedated, or adequate was used three times (Table 1). The Ramsay scale was the most commonly used scale, in 14 stud- ies, with a variant used in a further 7 studies. This is illustrated in Figure 2. In addition to the variation in scales used to assess sedation, there was variation in the recommended range of optimal sedation levels stated. Sedation requirements obviously differ among patients; nevertheless, the variation in recommended ranges in included studies indicates some uncertainty in what constitutes optimal sedation. Of the studies using the Ramsay scale, recommended ranges were 2 to 3 (recommended in two studies [21,22]), 2 to 4 (two studies [23,24]), 2 to 5 (two studies [25,26]), 3 to 4 (two studies [27,28]) and 4 to 5 (one study [29]), while three studies did not recommend specific levels but recommended that levels be optimised for each indi- vidual patient [30-32]. This variation was reflected in the other scales used; for studies recommending a modified Ramsay scale, recommended ranges were 1 to 4 [33], 3 to 4 [34], 4 [35], and 5 to 6 (the last range being specifically for seriously injured patients [36]) or targets optimised for each patient [37,38]. The stated SAS (Riker Sedation-Agitation Scale) tar- get level was 1 to 3 [39], 4 [40,41], or 3 to 4 [42]. Due to the number of studies recommending that optimal sedation state be determined individually for each patient, there was no com- parison possible for other scales. Figure 2 The frequency with which each sedation scale was used in the studies included in our systematic reviewThe frequency with which each sedation scale was used in the studies included in our systematic review. ICU, intensive care unit; MAAS, Motor Activity Assessment Scale; OAAS, Observer's Assessment of Alertness/Sedation Scale; RASS, Richmond Agitation Sedation Scale; SAS, Riker Sedation-Agitation Scale. 0 2 4 6 8 10 12 14 16 Ramsay Variant of Ramsay SAS Glasgow Coma scale (modified) Nurse judgment RASS Addenbrookes Bloomsbury Minnesota Sedation Assessment tool North Staffordshire ICU tool Comfort scale Brussels sedation scale MAAS OAAS Frequency of use of scale in studies included in review Sedation scale Critical Care Vol 13 No 6 Jackson et al. Page 4 of 14 (page number not for citation purposes) Table 1 Incidence of optimal and sub-optimal sedation in included studies Study Study design and comparisons made Number Treatment arms (if relevant) Incidence of sub-optimal sedation Incidence of over-sedation Incidence of under-sedation Incidence of optimal sedation Sedation scale/ monitoring system used Definition of optimal sedation Weinert, et al., 2007 [44] Cohort study 274 326 (2.6%) of 12,414 assessments. 111 patients (40%) had ≥ 1 rating of over- sedation. Patients were unarousable/ minimally arousable 32% of the time. 1,731 (13.9%) of 12,414 assessments. 211 (76.2%) had ≥ 1 rating of under-sedation. 10,357 (83%) of 12,414 Minnesota Sedation Assessment Tool nurse assessment Arousal level 3-5 (of 6-point scale) Martin, et al., 2006 [30] Cohort study 305 (from 220 ICUs) 42.6% of 49 patients sedated 24-72 hours, 39.5% of 157 patients sedated >72 hours, and 43.9% of 57 patients under weaning had significantly deeper sedation than desired level 5.2% of 157 patients sedated >72 hours and 3.5% of 57 patients under weaning had significantly lower sedation than desired level In patients sedated >72 hours, the desired Ramsay score was 0-4 in 44% of cases this was achieved in 28%; in 55% of patients, the desired value was 4-5, which was achieved in 68%; in 1% of patients, the desired score was 6, which was achieved in 6%. Ramsay scale Individual to each patient Payen, et al., 2007 [43] Cohort study 1,381 258 (57%) of 451 patients on sedation day 2; 169 (48%) of 355 patients on day 4; 109 (41%) of 266 patients on day 6 Multiple: most commonly Ramsay, RASS, Sedation- Agitation scale Over-sedation defined as Ramsay 5-6, RASS -5 or 4, Sedation- Agitation scale 1- 2 Sandiumenge, et al., 2000 [36] RCT/ observational study of sedative drugs 63 Midazolam 19 (7%) of 266 hours 247 (93%) of 266 hours Modified Ramsay scale Equivalent of Ramsay 5-6 (for deep sedation) 2% propofol 14 (9%) of 156 hours 142 (91%) of 156 hours Carrasco, et al., 1993 [26] RCT (with economic study) of sedative drugs 88 Midazolam 18% of time (hours) 82% of time (hours) Ramsay scale; Glasgow coma scale (modified by Cook and Palma) Ramsay scale 2-5, Glasgow coma scale 8-13 Critical Care Vol 13 No 6 Jackson et al. Page 5 of 14 (page number not for citation purposes) Propofol 7% of time (hours) 93% of time (hours) McCollam, et al., 1999 [23] RCT of sedative drugs 30 Lorazepam 32% of assessments 14% of assessments 18% of assessments 68% of assessments Ramsay scale Ramsay scale 2-4 Midazolam 21% of assessments 6% of assessments 16% of assessments 79% of assessments Propofol 38% of assessments 7% of assessments 31% of assessments 62% of assessments Chinachoti, et al., 2002 [40] RCT of sedative drugs 152 Remifentanil 28% of patients; 17.3% of time (hours) 13% of time (hours) 4% of time (hours) 78% of patients (without midazolam), 83% of time (hours) (maintenance phase) SAS SAS 4 with no or mild pain Morphine 27% of patients; 16% of time (hours) 13% of time (hours) 3% of time (hours) 73% of patients (without midazolam), 84% of time (hours) (maintenance phase) Harper, et al., 1991 [25] RCT of sedative drugs 37 Alfentanil low, moderate and high doses results reported together 4 patients had >10% of time at sedation level 6 3 patients had >10% of time at sedation level 1 Ramsay (assessed hourly) 2-5 Manley, et al., 1997 [46] RCT (and economic study) of sedative drugs 26 Morphine + midazolam 56.8% of time 43.2% of time North Staffordshire ICU (modification of Ramsay/ Addenbrooke's scores) 3-4 Alfentanil + propofol 57.8% of time 42.2% of time Millane, 1992 [21] RCT of sedative drugs 24 Isoflurane for 24 hours followed by propofol 3.4% Ramsay plus subjective nurse assessment 2-3 (plus subjective nurse assessment) Propofol for 24 hours followed by isoflurane 3.6% Muellejans, et al., 2004 [41] RCT of sedative drugs 152 Remifentanil 11.7% of time (hours) 88.3% of time (hours) SAS 4 Fentanyl 10.7% of time (hours) 89.3% of time (hours) Table 1 (Continued) Incidence of optimal and sub-optimal sedation in included studies Critical Care Vol 13 No 6 Jackson et al. Page 6 of 14 (page number not for citation purposes) Muellejans, et al., 2006 [47] RCT of sedative drugs 80 Remifentanil propofol 41% of time 28% of time 13% of time 59% of time 3 level sedation score specific to study Level 2 Midazolam fentanyl 30% of time 19% of time 11% of time 70% of time Chamorro, et al., 1996 [45] RCT of sedative drugs 98 Propofol 332 assessments 3% (after first hour) 332 assessments 76.5% effective, 20.5% acceptable Study-specific (modified Glasgow coma scale). Patients monitored at 1 and 6 hours and then every 12 hours. 4 = effective, 3 = acceptable less than 3 = ineffective Midazolam 355 assessments 7.6% 355 assessments 66.2% effective, 26.2% acceptable Barr, et al., 2001 [34] RCT of sedative drugs 24 Lorazepam 51% of time 47% of time 49% of time Modified Ramsay 3-4 (5-6 = over- sedation) Midazolam 31% of time 22% of time 69% of time Finfer, et al., 1999 [33] RCT of sedative drugs 40 Diazepam (intermittent) 9 (64.3%) of 14 patients; 15.0% of time (hours) 2.8% of time (hours) 21.1% of time (hours) 5 (35.7%) of 14 patients; 85.0% of time (hours) Modified Ramsay 1-4 Midazolam (continuous) 6 (35.3%) of 17 patients; 40.8% of time (hours) 14.8% of time (hours) 0% of time (hours) 11 (64.7%) of 17 patients; 59.2% of time (hours) Richman, et al., 2006 [37] RCT of sedative drugs 30 Midazolam Mean 9.1 hours/ day (SD 4.9) Modified Ramsay Individual to each patient Midazolam and fentanyl Mean 4.2 hours/ day (SD 2.4) Karabinis, et al., 2004 [39] RCT of sedative drugs 161 Remifentanil 4.4% of time 95.6% of time (median) SAS 1-3 Fentanyl 1.9% of time 98.1% of time (median) Morphine 1.0% of time 99.0% of time (median) Pandharipande, et al., 2007 [48], Pandharipande, et al., 2006 [59] RCT of sedative drugs 106 Dexmedetomidine 20% of patients according to nurse goals; 33% according to physician goals 15% of patients 80% of patients within 1 point of nurse goal; 67% within 1 point of physician goal RASS, confusion- assessment method for the ICU (CAM-ICU) Individual to each patient Table 1 (Continued) Incidence of optimal and sub-optimal sedation in included studies Critical Care Vol 13 No 6 Jackson et al. Page 7 of 14 (page number not for citation purposes) Lorazepam 33% of patients according to nurse goals; 45% according to physician goals 33% of patients 67% within 1 point of nurse goal; 55% within 1 point of physician goal Swart, et al., 1999 [50] RCT of sedative drugs 64 Lorazepam 13% of time 87.0% of time (SD 10.5) Addenbrooke's Hospital's ICU sedation scale Individual to each patient Midazolam 34% of time 66.2% of time (SD 23.1) Carson, et al., 2006 [22] RCT of sedative drugs 132 Intermittent lorazepam 42.8% (ventilator hours) 37.9% (ventilator hours) 15.1% (ventilator hours) Ramsay 2-3 Continuous propofol 49.9% (ventilator hours) 38.6% (ventilator hours) 11.5% (ventilator hours) Anis, et al., 2002 [31], Hall, et al., 2001 [60] RCT of sedative drugs 156 Propofol 39.8% of time 12.0% of time 11.2% of time 60.2% of time Ramsay Individual to each patient Midazolam 56.0% of time 18.4% of time 8.1% of time 44.0% of time Park, et al., 2007 [49] RCT of sedative drugs 134 (111 analysed) Analgesia-based sedation 50% of time 50% of time on SIMV (median) Assessor judgement Adequate judged as awake or easily rousable Hypnotic-based sedation 81% of time 19% of time on SIMV (median) Cigada, et al., 2005 [32] Observational study of sedative drugs 42 Propofol or midazolam with enteral hydroxyzine with or without supplemental lorazepam. IV drugs were tapered after 48 hours. 36.9% of assessments as judged by Ramsay score; 17% by nurse assessment 421 (24.6%) of 1,711 assessments (Ramsay score) 42 (7.3%) of 577 assessments (nurse judgement) 211 (12.3%) of 1,711 assessments (Ramsay score) 56 (9.8%) of 577 assessments (nurse judgement) 1,079 (63.1%) of 1,711 assessments (Ramsay score) 479 (83%) of 577 assessments (nurse judgement) Ramsay score plus nurse assessment Adequate sedation defined as the achievement of the planned Ramsay score or nurse judgement as adequate Barrientos-Vega, et al., 2001 [29] Observational study of sedative drugs 51 2% propofol (compared with historical cohort on 1% propofol not reported here) 8 (15.6%) of 51 patients judged therapeutic failure on 2% propofol (inadequate level of sedation) Ramsay score 4-5 MacLaren, et al., 2007 [42] Observational study of sedative drugs 40 Dexmedetomidine as adjunct to lorazepam/ midazolam/ propofol 35% of patients with dexmedetomidine; 52% without 12 (30%) patients with dexmedetomidine; 9 (23%) without 4 (10%) patients with dexmedetomidine; 12 (30%) without 65% of patients with dexmedetomidine; 48% without SAS 3-4 Table 1 (Continued) Incidence of optimal and sub-optimal sedation in included studies Critical Care Vol 13 No 6 Jackson et al. Page 8 of 14 (page number not for citation purposes) Shehabi, et al., 2004 [24] Observational study of sedative drugs 20 Dexmedetomidine with supplemental midazolam if required 455 (33%) of 1,381 assessments 97 (7%) of 1,381 assessments were Ramsay level 6 137 (10%) of 1,381 assessments were Ramsay level 1 926 (67%) of 1,381 Ramsay 2-4 Sackey, et al., 2004 [51] RCT of sedation devices 40 Isoflurane using AnaConDa 46% of time; nursing staff estimate 11% of time 44% of time 2% of time 54% of time; nursing staff estimate 89% of time Bloomsbury scale - 1 to +1 IV midazolam 41%; nursing staff estimate 13% of time 37% of time 4% of time 59% of time; nursing staff estimate 87% of time Walsh, et al., 2008 [52] Observational study of sedation devices 30 All sedated patients 137 (32.9%) of 416 assessments (Ramsay score 5- 6) 5 (1.2%) of 416 assessments (Ramsay score 1) Entropy Module/ Modified Ramsay scale None stated. Refers to guidelines suggesting 2-3 is adequate and heavy/over- sedated is 5-6. Hernández- Gancedo, et al., 2006 [28] Observational study of sedation scales 50 44% (66 cases) Ramsay level 6 25% (38 cases) Ramsay, Observer's Assessment of Alertness and Sedation Ramsay 3-4 Roustan, et al., 2005 [27] Observational study of sedation scales 40 All sedated patients treated with midazolam and morphine 93 (61.6%) of 151 records 19 (12.6%) of 151 records Ramsay, Comfort score, EEG Ramsay 3-4 McMurray, et al., 2004 [38] Observational study of sedation scales 122 Propofol- containing regimens 15.6% of time Mean 5.0% of time (SD 12.7) Mean 10.6% of time (SD 14.5) Mean 84.4% of time (SD 18.0) Modified Ramsay Individual to each patient Detriche, et al., 1999 [53] Before-after study of introduction of sedation protocol 55 Before 20 (30%) of 67 assessment days Brussels sedation scale 3-4 After protocol introduction 9 (12%) of 77 assessment days Costa, et al., 1994 [54] RCT of controlled and empirical sedation 40 Controlled 17% of time 83% of time Ramsay, and Glasgow coma scale modified by Cook and Palma Empirical 65% of time 35% of time MacLaren, et al., 2000 [35] Before-after comparison of sedation protocol 158 Before 22.4% (experience of anxiety or pain) Modified Ramsay 4 Table 1 (Continued) Incidence of optimal and sub-optimal sedation in included studies Critical Care Vol 13 No 6 Jackson et al. Page 9 of 14 (page number not for citation purposes) After 11.0% (P < 0.001) Tallgren, et al., 2006 [3] Before-after comparison of sedation protocol 53 Before reinforcement Median Ramsay level was 4 during the day and 5 at night, in contrast to the study's stated aim of Ramsay level 2-3 during the day and 3-4 at night Ramsay After reinforcement Median Ramsay level was 4 during the day and 5 at night, in contrast to the study's stated aim of Ramsay level 2-3 during the day and 3-4 at night Samuelson, et al., 2007 [61], Samuelson, et al., 2006 [62] Observational study 250 50% of patients had MAAS 0-2 (although 2 was target for study, 0- 1 could be viewed as over-sedated) 0% 39% of patients achieved MAAS 3 in ventilated period MAAS Stated 2-3 but results reported for patients achieving 3 EEG, electroencephalogram; ICU, intensive care unit; IV, intravenous; MAAS, Motor Activity Assessment Scale; RASS, Richmond Agitation-Sedation Scale; RCT, randomised controlled trial; SAS, Riker Sedation-Agitation Scale; SD, standard deviation; SIMV, synchronised intermittent mandatory ventilation. Table 1 (Continued) Incidence of optimal and sub-optimal sedation in included studies Critical Care Vol 13 No 6 Jackson et al. Page 10 of 14 (page number not for citation purposes) Incidence of sub-optimal sedation Table 1 lists the study design, sedation assessment scale or tool used, and incidence of sub-optimal sedation reported by studies. As stated above, we used individual study definitions of optimal and sub-optimal sedation because of the fact that optimal sedation levels are likely to vary by study setting. The three observational studies that investigated the epidemi- ology of sedation were considered to be the most relevant to the study question as their specific aim was to investigate clin- ical sedation practice rather than practice within the confines of a trial, where more frequent monitoring and the Hawthorne effect could contribute to improving standards. A survey of practice across 44 ICUs in France also found a high incidence of deep sedation, in 41% to 57% of readings over a 6-day period [43]. This study highlighted the risks of prolonged deep sedation, which, however, was not specifi- cally defined as over-sedation. Results from these three stud- ies indicate that 30% to 60% of sedation assessments indicate 'deep' or 'over' sedation, although precise description of the prevalence is confounded by imprecise definition or health care worker perceptions. These studies clearly indicate an excess of over-sedation compared with under-sedation. Martin and colleagues [30] conducted a postal survey of 220 ICUs in Germany. This study found that 42.6% of patients sedated between 24 and 72 hours and 39.5% of patients sedated over 72 hours were over-sedated; the incidence of under-sedation was much lower (<6%). In the US-based study of Weinert and colleagues [44], the aim was to compare subjective and objective ratings of sedation. Subjects provided 12,414 sedation assessments and were judged by nurses to be sub-optimally sedated in 17% of assessments, over-sedated in 2.6%, and under-sedated in 13.9%. Critically, however, patients were unrousable or mini- mally rousable just under one third of the time, indicating a high incidence of deep sedation. This finding illustrates the importance of the perception of the health care worker or assessor or both in describing the prevalence of sub-optimal sedation. The remaining included studies comprised studies of sedative drugs [21-26,29,31-34,36,37,39-42,45-50], studies investi- gating different sedation devices or scales [27,28,38,51,52], and studies looking at the introduction of a sedation guideline or protocol [3,35,53,54]. Studies varied by design and aim, by sedatives used, by scales and definitions of sub-optimal seda- tion used, and by the way incidence was reported (as a pro- portion of measurements, patients, or time). While these studies did not necessarily have the incidence of sub-optimal sedation as their primary focus, the data in such studies were considered to be of interest to the inclusive scope of this review. Although studies of sedative drugs or of the introduc- tion of guidelines or protocols may not give an accurate esti- mate of the incidence of sub-optimal sedation within routine clinical practice, they nevertheless show that it does occur and can give an impression of the extent to which it may be a prob- lem, even in settings that could be reasonably expected to be more controlled than in routine practice. The incidence of sub- optimal sedation reported in these studies is summarised in Figure 3 (separated by study and treatment arm where rele- vant). The reported incidence varied from 1% [39] to 75% [28], with the majority reporting an incidence of over 20%. The incidence of over- and under-sedation was similarly variable, and figures of between 2.8% and 44% for over-sedation [28,33,51] and between 2% and 31% for under-sedation [23,51] were reported. A further study [2] that looked at the introduction of a sedation guideline did not record the inci- dence of sub-optimal sedation but recorded the median Ram- say scale values. These were 4 during the day and 5 at night, in contrast to the study's stated aim of Ramsay levels of 2 to 3 during the day and 3 to 4 at night; this study again noted a possible tendency toward over-sedation of patients. Impor- tantly, there was no change in this tendency before and after reinforcement of the guideline, suggesting that this was insuf- ficient to improve sedation practice [3]. Discussion Our systematic review identified few studies that specifically described the epidemiology of sedation during ICU care. Description of the incidence of sub-optimal sedation and over- and under-sedation was difficult due to variation in the use of these terms within individual studies. Overall, available data suggest a high incidence of over-sedation in ICUs, potentially present at 40% to 60% of assessments. A lower reported inci- dence of sub-optimal sedation across most studies suggests that health care workers consider deep levels of sedation appropriate for many patients. The quality of published studies was low. There was wide var- iation in the method used to assess sedation state, the fre- quency of measurement, and the stated response to evaluations. In addition, the completeness of data in relation to entire ICU populations was usually not stated, introducing the potential for selection bias. Only three cohort studies were found. The importance of selection or inclusion bias was low- est with this study design. All of these indicated a substantial incidence of sub-optimal sedation, with over-sedation being more common (33% to 57%). Notably, one study reported that nurse assessment of sedation found a low incidence of over-sedation, which appeared at odds with the fact that in one third of measurements patients were unrousable or mini- mally rousable. A difference in perceptions of what constitutes optimal sedation between different health care worker groups and between individual health care workers is also likely to affect the reported incidence of sub-optimal sedation. This finding emphasises the importance of using sedation-assess- ment methods that have high validity and low inter-rater varia- [...]... American College of Critical Care Medicine of the Society of Critical Care Medicine, American Society of Health-System Pharmacists, American College of Chest Physicians: Clinical practice guidelines for the sustained use of sedatives and analgesics in the critically ill adult Am J Health Syst Pharm 2002, 59:150-178 Feeley K, Gardner A: Sedation and analgesia management for mechanically ventilated adults:... sub-optimally sedated and, specifically, that the incidence of over -sedation remains high The strong associations between sedation practice, especially over -sedation, and adverse patient outcomes suggest that a more uniform approach to monitoring depth and quality of sedation will improve quality of care Key messages Authors' information TW is a professor of anaesthetics and critical care at Edinburgh... manuscript revisions All authors read and approved the final manuscript Conclusions Our review indicates the poor quality of epidemiological data concerning current sedation practice and the incidence of sub-optimal sedation A key issue is the standardisation of methods of assessment and definitions of optimal sedation Despite this, available data suggest that many patients in ICUs are considered sub-optimally... HE, Merilainen PT: An assessment of the validity of spectral entropy as a measure of sedation state in mechanically ventilated critically ill patients Intensive Care Med 2008, 34:308-315 53 Detriche O, Berré J, Massaut J, Vincent JL: The Brussels sedation scale: use of a simple clinical sedation scale can avoid excessive sedation in patients undergoing mechanical ventilation in the intensive care unit... guideline manual: analgesia and sedation in the ICU 2003 [http://www.uphs.upenn.edu/surgery/trauma/scc/protocol/Anal gesia.pdf] Shapiro BA, Warren J, Egol AB, Greenbaum DM, Jacobi J, Nasraway SA, Schein RM, Spevetz A, Stone JR: Practice parameters for intravenous analgesia and sedation for adult patients in the intensive care unit: an executive summary Society of Critical Care Medicine Crit Care Med 1995,... percentage of expected Ramsay scale recordings made, but only to 71% of expected recordings that were actually made, indicating that formal sedation assessments were still not carried out as regularly as they should have been These studies suggest that, despite recent evidence supporting the avoidance of over -sedation [57,58], the use of systematic approaches to measure sedation state and optimise sedation. .. Task Force of the American College of Critical Care Medicine (ACCM) of the Society of Critical Care Medicine (SCCM), American Society of Health-System Pharmacists (ASHP), American College of Chest Physicians: Clinical practice guidelines for the sustained use of sedative and analgesics in the critically ill adult Crit Care Med 2002, 30:119-141 3 Tallgren M, Pettila V, Hynninen M, Tallgren M, Pettila... study-specific definitions, of greater than 20% These studies confirm the findings of the observational cohort studies and suggest high levels of sub-optimal sedation during routine care Improving sedation management through sedation protocols and interventions such as daily interruption of sedation is an increasing focus of quality improvement initiatives in critical care in some health care systems... [1,56,57] Sedation protocols and scales are increasingly, though not universally, used A review of German hospitals by Martin and colleagues [6] showed increases in the use of sedation protocols (from 21% of hospitals to 46%) and in the use of sedation scales (from 8% to 51%) over the period of 2002 to 2006 In Finland, Tallgren and colleagues [3] reported that reinforcing a sedation guideline increased the. .. analgo -sedation in intensive care unit Minerva Anestesiol 2006, 72:769-805 Knape JT, Adriaensen H, van Aken H, Blunnie WP, Carlsson C, Dupont M, Pasch T, Board of Anaesthesiology of the European Union of Medical Specialists: Guidelines for sedation and/or analgesia by non-anaesthesiology doctors Eur J Anaesthesiol 2007, 24:563-567 University of Pennsylvania Medical Center: Clinical practice guideline . reinforcement Median Ramsay level was 4 during the day and 5 at night, in contrast to the study's stated aim of Ramsay level 2-3 during the day and 3-4 at night Ramsay After reinforcement Median. TS, Ramsay P, Lapinlampi TP, Sarkela MO, Viertio-Oja HE, Merilainen PT: An assessment of the validity of spectral entropy as a measure of sedation state in mechanically ventilated crit- ically ill. optimal and sub-optimal sedation because of the fact that optimal sedation levels are likely to vary by study setting. The three observational studies that investigated the epidemi- ology of sedation